This invention relates to concrete pumps, and, more particularly, to a concrete pump with a pivotable S-valve and hopper assembly.
Concrete pumps are well known in the construction industry and are used for pumping concrete or other pumpable construction materials. Concrete pumps are described, for example, in U.S. Pat. Nos. 3,612,730, 3,897,180, and 4,241,641.
Most concrete pumps which are currently being manufactured include two concrete pumping cylinders and an S-shaped tube valve for alternately connecting the outlet end of each pumping cylinder to the discharge conduit of the concrete pump. The S-tube valve is pivotally mounted in a concrete hopper. As the piston in one of the pumping cylinders moves toward the hopper to pump concrete through the S-tube valve to the discharge conduit, the piston in the other pumping cylinder retracts away from the hopper to draw concrete into the cylinder.
A major problem with the S-tube valve is clean-up. Material builds up and hardens in the bottom or inlet end of the tube, and the hardened material is difficult to remove because of the curved shape of the tube. The problem is particularly acute with small diameter S-tubes.
The curved tube also makes it difficult to service the outlet end of the pumping cylinders. The pumping pistons carry seals which must be changed from time to time.